fs/isofs/rock.c - kernel/msm-4.9 - Gitiles

 /*
  *  linux/fs/isofs/rock.c
  *
  *  (C) 1992, 1993  Eric Youngdale
  *
  *  Rock Ridge Extensions to iso9660
  */

 #include <linux/slab.h>
 #include <linux/pagemap.h>

 #include "isofs.h"
 #include "rock.h"

 /*
  * These functions are designed to read the system areas of a directory record
  * and extract relevant information.  There are different functions provided
  * depending upon what information we need at the time.  One function fills
  * out an inode structure, a second one extracts a filename, a third one
  * returns a symbolic link name, and a fourth one returns the extent number
  * for the file.
  */

 #define SIG(A,B) ((A) | ((B) << 8))	/* isonum_721() */

 struct rock_state {
 	void *buffer;
 	unsigned char *chr;
 	int len;
 	int cont_size;
 	int cont_extent;
 	int cont_offset;
 	int cont_loops;
 	struct inode *inode;
 };

 /*
  * This is a way of ensuring that we have something in the system
  * use fields that is compatible with Rock Ridge.  Return zero on success.
  */

 static int check_sp(struct rock_ridge *rr, struct inode *inode)
 {
 	if (rr->u.SP.magic[0] != 0xbe)
 		return -1;
 	if (rr->u.SP.magic[1] != 0xef)
 		return -1;
 	ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
 	return 0;
 }

 static void setup_rock_ridge(struct iso_directory_record *de,
 			struct inode *inode, struct rock_state *rs)
 {
 	rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
 	if (rs->len & 1)
 		(rs->len)++;
 	rs->chr = (unsigned char *)de + rs->len;
 	rs->len = *((unsigned char *)de) - rs->len;
 	if (rs->len < 0)
 		rs->len = 0;

 	if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
 		rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
 		rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
 		if (rs->len < 0)
 			rs->len = 0;
 	}
 }

 static void init_rock_state(struct rock_state *rs, struct inode *inode)
 {
 	memset(rs, 0, sizeof(*rs));
 	rs->inode = inode;
 }

 /* Maximum number of Rock Ridge continuation entries */
 #define RR_MAX_CE_ENTRIES 32

 /*
  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  * and -ve on error.
  */
 static int rock_continue(struct rock_state *rs)
 {
 	int ret = 1;
 	int blocksize = 1 << rs->inode->i_blkbits;
 	const int min_de_size = offsetof(struct rock_ridge, u);

 	kfree(rs->buffer);
 	rs->buffer = NULL;

 	if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
 	    (unsigned)rs->cont_size > blocksize ||
 	    (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
 		printk(KERN_NOTICE "rock: corrupted directory entry. "
 			"extent=%d, offset=%d, size=%d\n",
 			rs->cont_extent, rs->cont_offset, rs->cont_size);
 		ret = -EIO;
 		goto out;
 	}

 	if (rs->cont_extent) {
 		struct buffer_head *bh;

 		rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
 		if (!rs->buffer) {
 			ret = -ENOMEM;
 			goto out;
 		}
 		ret = -EIO;
 		if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
 			goto out;
 		bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
 		if (bh) {
 			memcpy(rs->buffer, bh->b_data + rs->cont_offset,
 					rs->cont_size);
 			put_bh(bh);
 			rs->chr = rs->buffer;
 			rs->len = rs->cont_size;
 			rs->cont_extent = 0;
 			rs->cont_size = 0;
 			rs->cont_offset = 0;
 			return 0;
 		}
 		printk("Unable to read rock-ridge attributes\n");
 	}
 out:
 	kfree(rs->buffer);
 	rs->buffer = NULL;
 	return ret;
 }

 /*
  * We think there's a record of type `sig' at rs->chr.  Parse the signature
  * and make sure that there's really room for a record of that type.
  */
 static int rock_check_overflow(struct rock_state *rs, int sig)
 {
 	int len;

 	switch (sig) {
 	case SIG('S', 'P'):
 		len = sizeof(struct SU_SP_s);
 		break;
 	case SIG('C', 'E'):
 		len = sizeof(struct SU_CE_s);
 		break;
 	case SIG('E', 'R'):
 		len = sizeof(struct SU_ER_s);
 		break;
 	case SIG('R', 'R'):
 		len = sizeof(struct RR_RR_s);
 		break;
 	case SIG('P', 'X'):
 		len = sizeof(struct RR_PX_s);
 		break;
 	case SIG('P', 'N'):
 		len = sizeof(struct RR_PN_s);
 		break;
 	case SIG('S', 'L'):
 		len = sizeof(struct RR_SL_s);
 		break;
 	case SIG('N', 'M'):
 		len = sizeof(struct RR_NM_s);
 		break;
 	case SIG('C', 'L'):
 		len = sizeof(struct RR_CL_s);
 		break;
 	case SIG('P', 'L'):
 		len = sizeof(struct RR_PL_s);
 		break;
 	case SIG('T', 'F'):
 		len = sizeof(struct RR_TF_s);
 		break;
 	case SIG('Z', 'F'):
 		len = sizeof(struct RR_ZF_s);
 		break;
 	default:
 		len = 0;
 		break;
 	}
 	len += offsetof(struct rock_ridge, u);
 	if (len > rs->len) {
 		printk(KERN_NOTICE "rock: directory entry would overflow "
 				"storage\n");
 		printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
 				sig, len, rs->len);
 		return -EIO;
 	}
 	return 0;
 }

 /*
  * return length of name field; 0: not found, -1: to be ignored
  */
 int get_rock_ridge_filename(struct iso_directory_record *de,
 			    char *retname, struct inode *inode)
 {
 	struct rock_state rs;
 	struct rock_ridge *rr;
 	int sig;
 	int retnamlen = 0;
 	int truncate = 0;
 	int ret = 0;

 	if (!ISOFS_SB(inode->i_sb)->s_rock)
 		return 0;
 	*retname = 0;

 	init_rock_state(&rs, inode);
 	setup_rock_ridge(de, inode, &rs);
 repeat:

 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
 		rr = (struct rock_ridge *)rs.chr;
 		/*
 		 * Ignore rock ridge info if rr->len is out of range, but
 		 * don't return -EIO because that would make the file
 		 * invisible.
 		 */
 		if (rr->len < 3)
 			goto out;	/* Something got screwed up here */
 		sig = isonum_721(rs.chr);
 		if (rock_check_overflow(&rs, sig))
 			goto eio;
 		rs.chr += rr->len;
 		rs.len -= rr->len;
 		/*
 		 * As above, just ignore the rock ridge info if rr->len
 		 * is bogus.
 		 */
 		if (rs.len < 0)
 			goto out;	/* Something got screwed up here */

 		switch (sig) {
 		case SIG('R', 'R'):
 			if ((rr->u.RR.flags[0] & RR_NM) == 0)
 				goto out;
 			break;
 		case SIG('S', 'P'):
 			if (check_sp(rr, inode))
 				goto out;
 			break;
 		case SIG('C', 'E'):
 			rs.cont_extent = isonum_733(rr->u.CE.extent);
 			rs.cont_offset = isonum_733(rr->u.CE.offset);
 			rs.cont_size = isonum_733(rr->u.CE.size);
 			break;
 		case SIG('N', 'M'):
 			if (truncate)
 				break;
 			if (rr->len < 5)
 				break;
 			/*
 			 * If the flags are 2 or 4, this indicates '.' or '..'.
 			 * We don't want to do anything with this, because it
 			 * screws up the code that calls us.  We don't really
 			 * care anyways, since we can just use the non-RR
 			 * name.
 			 */
 			if (rr->u.NM.flags & 6)
 				break;

 			if (rr->u.NM.flags & ~1) {
 				printk("Unsupported NM flag settings (%d)\n",
 					rr->u.NM.flags);
 				break;
 			}
 			if ((strlen(retname) + rr->len - 5) >= 254) {
 				truncate = 1;
 				break;
 			}
 			strncat(retname, rr->u.NM.name, rr->len - 5);
 			retnamlen += rr->len - 5;
 			break;
 		case SIG('R', 'E'):
 			kfree(rs.buffer);
 			return -1;
 		default:
 			break;
 		}
 	}
 	ret = rock_continue(&rs);
 	if (ret == 0)
 		goto repeat;
 	if (ret == 1)
 		return retnamlen; /* If 0, this file did not have a NM field */
 out:
 	kfree(rs.buffer);
 	return ret;
 eio:
 	ret = -EIO;
 	goto out;
 }

 #define RR_REGARD_XA 1
 #define RR_RELOC_DE 2

 static int
 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 				struct inode *inode, int flags)
 {
 	int symlink_len = 0;
 	int cnt, sig;
 	unsigned int reloc_block;
 	struct inode *reloc;
 	struct rock_ridge *rr;
 	int rootflag;
 	struct rock_state rs;
 	int ret = 0;

 	if (!ISOFS_SB(inode->i_sb)->s_rock)
 		return 0;

 	init_rock_state(&rs, inode);
 	setup_rock_ridge(de, inode, &rs);
 	if (flags & RR_REGARD_XA) {
 		rs.chr += 14;
 		rs.len -= 14;
 		if (rs.len < 0)
 			rs.len = 0;
 	}

 repeat:
 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
 		rr = (struct rock_ridge *)rs.chr;
 		/*
 		 * Ignore rock ridge info if rr->len is out of range, but
 		 * don't return -EIO because that would make the file
 		 * invisible.
 		 */
 		if (rr->len < 3)
 			goto out;	/* Something got screwed up here */
 		sig = isonum_721(rs.chr);
 		if (rock_check_overflow(&rs, sig))
 			goto eio;
 		rs.chr += rr->len;
 		rs.len -= rr->len;
 		/*
 		 * As above, just ignore the rock ridge info if rr->len
 		 * is bogus.
 		 */
 		if (rs.len < 0)
 			goto out;	/* Something got screwed up here */

 		switch (sig) {
 #ifndef CONFIG_ZISOFS		/* No flag for SF or ZF */
 		case SIG('R', 'R'):
 			if ((rr->u.RR.flags[0] &
 			     (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 				goto out;
 			break;
 #endif
 		case SIG('S', 'P'):
 			if (check_sp(rr, inode))
 				goto out;
 			break;
 		case SIG('C', 'E'):
 			rs.cont_extent = isonum_733(rr->u.CE.extent);
 			rs.cont_offset = isonum_733(rr->u.CE.offset);
 			rs.cont_size = isonum_733(rr->u.CE.size);
 			break;
 		case SIG('E', 'R'):
 			ISOFS_SB(inode->i_sb)->s_rock = 1;
 			printk(KERN_DEBUG "ISO 9660 Extensions: ");
 			{
 				int p;
 				for (p = 0; p < rr->u.ER.len_id; p++)
 					printk("%c", rr->u.ER.data[p]);
 			}
 			printk("\n");
 			break;
 		case SIG('P', 'X'):
 			inode->i_mode = isonum_733(rr->u.PX.mode);
 			set_nlink(inode, isonum_733(rr->u.PX.n_links));
 			i_uid_write(inode, isonum_733(rr->u.PX.uid));
 			i_gid_write(inode, isonum_733(rr->u.PX.gid));
 			break;
 		case SIG('P', 'N'):
 			{
 				int high, low;
 				high = isonum_733(rr->u.PN.dev_high);
 				low = isonum_733(rr->u.PN.dev_low);
 				/*
 				 * The Rock Ridge standard specifies that if
 				 * sizeof(dev_t) <= 4, then the high field is
 				 * unused, and the device number is completely
 				 * stored in the low field.  Some writers may
 				 * ignore this subtlety,
 				 * and as a result we test to see if the entire
 				 * device number is
 				 * stored in the low field, and use that.
 				 */
 				if ((low & ~0xff) && high == 0) {
 					inode->i_rdev =
 					    MKDEV(low >> 8, low & 0xff);
 				} else {
 					inode->i_rdev =
 					    MKDEV(high, low);
 				}
 			}
 			break;
 		case SIG('T', 'F'):
 			/*
 			 * Some RRIP writers incorrectly place ctime in the
 			 * TF_CREATE field. Try to handle this correctly for
 			 * either case.
 			 */
 			/* Rock ridge never appears on a High Sierra disk */
 			cnt = 0;
 			if (rr->u.TF.flags & TF_CREATE) {
 				inode->i_ctime.tv_sec =
 				    iso_date(rr->u.TF.times[cnt++].time,
 					     0);
 				inode->i_ctime.tv_nsec = 0;
 			}
 			if (rr->u.TF.flags & TF_MODIFY) {
 				inode->i_mtime.tv_sec =
 				    iso_date(rr->u.TF.times[cnt++].time,
 					     0);
 				inode->i_mtime.tv_nsec = 0;
 			}
 			if (rr->u.TF.flags & TF_ACCESS) {
 				inode->i_atime.tv_sec =
 				    iso_date(rr->u.TF.times[cnt++].time,
 					     0);
 				inode->i_atime.tv_nsec = 0;
 			}
 			if (rr->u.TF.flags & TF_ATTRIBUTES) {
 				inode->i_ctime.tv_sec =
 				    iso_date(rr->u.TF.times[cnt++].time,
 					     0);
 				inode->i_ctime.tv_nsec = 0;
 			}
 			break;
 		case SIG('S', 'L'):
 			{
 				int slen;
 				struct SL_component *slp;
 				struct SL_component *oldslp;
 				slen = rr->len - 5;
 				slp = &rr->u.SL.link;
 				inode->i_size = symlink_len;
 				while (slen > 1) {
 					rootflag = 0;
 					switch (slp->flags & ~1) {
 					case 0:
 						inode->i_size +=
 						    slp->len;
 						break;
 					case 2:
 						inode->i_size += 1;
 						break;
 					case 4:
 						inode->i_size += 2;
 						break;
 					case 8:
 						rootflag = 1;
 						inode->i_size += 1;
 						break;
 					default:
 						printk("Symlink component flag "
 							"not implemented\n");
 					}
 					slen -= slp->len + 2;
 					oldslp = slp;
 					slp = (struct SL_component *)
 						(((char *)slp) + slp->len + 2);

 					if (slen < 2) {
 						if (((rr->u.SL.
 						      flags & 1) != 0)
 						    &&
 						    ((oldslp->
 						      flags & 1) == 0))
 							inode->i_size +=
 							    1;
 						break;
 					}

 					/*
 					 * If this component record isn't
 					 * continued, then append a '/'.
 					 */
 					if (!rootflag
 					    && (oldslp->flags & 1) == 0)
 						inode->i_size += 1;
 				}
 			}
 			symlink_len = inode->i_size;
 			break;
 		case SIG('R', 'E'):
 			printk(KERN_WARNING "Attempt to read inode for "
 					"relocated directory\n");
 			goto out;
 		case SIG('C', 'L'):
 			if (flags & RR_RELOC_DE) {
 				printk(KERN_ERR
 				       "ISOFS: Recursive directory relocation "
 				       "is not supported\n");
 				goto eio;
 			}
 			reloc_block = isonum_733(rr->u.CL.location);
 			if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
 			    ISOFS_I(inode)->i_iget5_offset == 0) {
 				printk(KERN_ERR
 				       "ISOFS: Directory relocation points to "
 				       "itself\n");
 				goto eio;
 			}
 			ISOFS_I(inode)->i_first_extent = reloc_block;
 			reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
 			if (IS_ERR(reloc)) {
 				ret = PTR_ERR(reloc);
 				goto out;
 			}
 			inode->i_mode = reloc->i_mode;
 			set_nlink(inode, reloc->i_nlink);
 			inode->i_uid = reloc->i_uid;
 			inode->i_gid = reloc->i_gid;
 			inode->i_rdev = reloc->i_rdev;
 			inode->i_size = reloc->i_size;
 			inode->i_blocks = reloc->i_blocks;
 			inode->i_atime = reloc->i_atime;
 			inode->i_ctime = reloc->i_ctime;
 			inode->i_mtime = reloc->i_mtime;
 			iput(reloc);
 			break;
 #ifdef CONFIG_ZISOFS
 		case SIG('Z', 'F'): {
 			int algo;

 			if (ISOFS_SB(inode->i_sb)->s_nocompress)
 				break;
 			algo = isonum_721(rr->u.ZF.algorithm);
 			if (algo == SIG('p', 'z')) {
 				int block_shift =
 					isonum_711(&rr->u.ZF.parms[1]);
 				if (block_shift > 17) {
 					printk(KERN_WARNING "isofs: "
 						"Can't handle ZF block "
 						"size of 2^%d\n",
 						block_shift);
 				} else {
 					/*
 					 * Note: we don't change
 					 * i_blocks here
 					 */
 					ISOFS_I(inode)->i_file_format =
 						isofs_file_compressed;
 					/*
 					 * Parameters to compression
 					 * algorithm (header size,
 					 * block size)
 					 */
 					ISOFS_I(inode)->i_format_parm[0] =
 						isonum_711(&rr->u.ZF.parms[0]);
 					ISOFS_I(inode)->i_format_parm[1] =
 						isonum_711(&rr->u.ZF.parms[1]);
 					inode->i_size =
 					    isonum_733(rr->u.ZF.
 						       real_size);
 				}
 			} else {
 				printk(KERN_WARNING
 				       "isofs: Unknown ZF compression "
 						"algorithm: %c%c\n",
 				       rr->u.ZF.algorithm[0],
 				       rr->u.ZF.algorithm[1]);
 			}
 			break;
 		}
 #endif
 		default:
 			break;
 		}
 	}
 	ret = rock_continue(&rs);
 	if (ret == 0)
 		goto repeat;
 	if (ret == 1)
 		ret = 0;
 out:
 	kfree(rs.buffer);
 	return ret;
 eio:
 	ret = -EIO;
 	goto out;
 }

 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 {
 	int slen;
 	int rootflag;
 	struct SL_component *oldslp;
 	struct SL_component *slp;
 	slen = rr->len - 5;
 	slp = &rr->u.SL.link;
 	while (slen > 1) {
 		rootflag = 0;
 		switch (slp->flags & ~1) {
 		case 0:
 			if (slp->len > plimit - rpnt)
 				return NULL;
 			memcpy(rpnt, slp->text, slp->len);
 			rpnt += slp->len;
 			break;
 		case 2:
 			if (rpnt >= plimit)
 				return NULL;
 			*rpnt++ = '.';
 			break;
 		case 4:
 			if (2 > plimit - rpnt)
 				return NULL;
 			*rpnt++ = '.';
 			*rpnt++ = '.';
 			break;
 		case 8:
 			if (rpnt >= plimit)
 				return NULL;
 			rootflag = 1;
 			*rpnt++ = '/';
 			break;
 		default:
 			printk("Symlink component flag not implemented (%d)\n",
 			       slp->flags);
 		}
 		slen -= slp->len + 2;
 		oldslp = slp;
 		slp = (struct SL_component *)((char *)slp + slp->len + 2);

 		if (slen < 2) {
 			/*
 			 * If there is another SL record, and this component
 			 * record isn't continued, then add a slash.
 			 */
 			if ((!rootflag) && (rr->u.SL.flags & 1) &&
 			    !(oldslp->flags & 1)) {
 				if (rpnt >= plimit)
 					return NULL;
 				*rpnt++ = '/';
 			}
 			break;
 		}

 		/*
 		 * If this component record isn't continued, then append a '/'.
 		 */
 		if (!rootflag && !(oldslp->flags & 1)) {
 			if (rpnt >= plimit)
 				return NULL;
 			*rpnt++ = '/';
 		}
 	}
 	return rpnt;
 }

 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
 			   int relocated)
 {
 	int flags = relocated ? RR_RELOC_DE : 0;
 	int result = parse_rock_ridge_inode_internal(de, inode, flags);

 	/*
 	 * if rockridge flag was reset and we didn't look for attributes
 	 * behind eventual XA attributes, have a look there
 	 */
 	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 	    && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 		result = parse_rock_ridge_inode_internal(de, inode,
 							 flags | RR_REGARD_XA);
 	}
 	return result;
 }

 /*
  * readpage() for symlinks: reads symlink contents into the page and either
  * makes it uptodate and returns 0 or returns error (-EIO)
  */
 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct iso_inode_info *ei = ISOFS_I(inode);
 	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
 	char *link = kmap(page);
 	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 	struct buffer_head *bh;
 	char *rpnt = link;
 	unsigned char *pnt;
 	struct iso_directory_record *raw_de;
 	unsigned long block, offset;
 	int sig;
 	struct rock_ridge *rr;
 	struct rock_state rs;
 	int ret;

 	if (!sbi->s_rock)
 		goto error;

 	init_rock_state(&rs, inode);
 	block = ei->i_iget5_block;
 	bh = sb_bread(inode->i_sb, block);
 	if (!bh)
 		goto out_noread;

 	offset = ei->i_iget5_offset;
 	pnt = (unsigned char *)bh->b_data + offset;

 	raw_de = (struct iso_directory_record *)pnt;

 	/*
 	 * If we go past the end of the buffer, there is some sort of error.
 	 */
 	if (offset + *pnt > bufsize)
 		goto out_bad_span;

 	/*
 	 * Now test for possible Rock Ridge extensions which will override
 	 * some of these numbers in the inode structure.
 	 */

 	setup_rock_ridge(raw_de, inode, &rs);

 repeat:
 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
 		rr = (struct rock_ridge *)rs.chr;
 		if (rr->len < 3)
 			goto out;	/* Something got screwed up here */
 		sig = isonum_721(rs.chr);
 		if (rock_check_overflow(&rs, sig))
 			goto out;
 		rs.chr += rr->len;
 		rs.len -= rr->len;
 		if (rs.len < 0)
 			goto out;	/* corrupted isofs */

 		switch (sig) {
 		case SIG('R', 'R'):
 			if ((rr->u.RR.flags[0] & RR_SL) == 0)
 				goto out;
 			break;
 		case SIG('S', 'P'):
 			if (check_sp(rr, inode))
 				goto out;
 			break;
 		case SIG('S', 'L'):
 			rpnt = get_symlink_chunk(rpnt, rr,
 						 link + (PAGE_SIZE - 1));
 			if (rpnt == NULL)
 				goto out;
 			break;
 		case SIG('C', 'E'):
 			/* This tells is if there is a continuation record */
 			rs.cont_extent = isonum_733(rr->u.CE.extent);
 			rs.cont_offset = isonum_733(rr->u.CE.offset);
 			rs.cont_size = isonum_733(rr->u.CE.size);
 		default:
 			break;
 		}
 	}
 	ret = rock_continue(&rs);
 	if (ret == 0)
 		goto repeat;
 	if (ret < 0)
 		goto fail;

 	if (rpnt == link)
 		goto fail;
 	brelse(bh);
 	*rpnt = '\0';
 	SetPageUptodate(page);
 	kunmap(page);
 	unlock_page(page);
 	return 0;

 	/* error exit from macro */
 out:
 	kfree(rs.buffer);
 	goto fail;
 out_noread:
 	printk("unable to read i-node block");
 	goto fail;
 out_bad_span:
 	printk("symlink spans iso9660 blocks\n");
 fail:
 	brelse(bh);
 error:
 	SetPageError(page);
 	kunmap(page);
 	unlock_page(page);
 	return -EIO;
 }

 const struct address_space_operations isofs_symlink_aops = {
 	.readpage = rock_ridge_symlink_readpage
 };
	/*
	* linux/fs/isofs/rock.c
	*
	* (C) 1992, 1993 Eric Youngdale
	*
	* Rock Ridge Extensions to iso9660
	*/

	#include <linux/slab.h>
	#include <linux/pagemap.h>

	#include "isofs.h"
	#include "rock.h"

	/*
	* These functions are designed to read the system areas of a directory record
	* and extract relevant information. There are different functions provided
	* depending upon what information we need at the time. One function fills
	* out an inode structure, a second one extracts a filename, a third one
	* returns a symbolic link name, and a fourth one returns the extent number
	* for the file.
	*/

	#define SIG(A,B) ((A) \| ((B) << 8)) /* isonum_721() */

	struct rock_state {
	void *buffer;
	unsigned char *chr;
	int len;
	int cont_size;
	int cont_extent;
	int cont_offset;
	int cont_loops;
	struct inode *inode;
	};

	/*
	* This is a way of ensuring that we have something in the system
	* use fields that is compatible with Rock Ridge. Return zero on success.
	*/

	static int check_sp(struct rock_ridge rr, struct inode inode)
	{
	if (rr->u.SP.magic[0] != 0xbe)
	return -1;
	if (rr->u.SP.magic[1] != 0xef)
	return -1;
	ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
	return 0;
	}

	static void setup_rock_ridge(struct iso_directory_record *de,
	struct inode inode, struct rock_state rs)
	{
	rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
	if (rs->len & 1)
	(rs->len)++;
	rs->chr = (unsigned char *)de + rs->len;
	rs->len = ((unsigned char )de) - rs->len;
	if (rs->len < 0)
	rs->len = 0;

	if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
	rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
	rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
	if (rs->len < 0)
	rs->len = 0;
	}
	}

	static void init_rock_state(struct rock_state rs, struct inode inode)
	{
	memset(rs, 0, sizeof(*rs));
	rs->inode = inode;
	}

	/* Maximum number of Rock Ridge continuation entries */
	#define RR_MAX_CE_ENTRIES 32

	/*
	* Returns 0 if the caller should continue scanning, 1 if the scan must end
	* and -ve on error.
	*/
	static int rock_continue(struct rock_state *rs)
	{
	int ret = 1;
	int blocksize = 1 << rs->inode->i_blkbits;
	const int min_de_size = offsetof(struct rock_ridge, u);

	kfree(rs->buffer);
	rs->buffer = NULL;

	if ((unsigned)rs->cont_offset > blocksize - min_de_size \|\|
	(unsigned)rs->cont_size > blocksize \|\|
	(unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
	printk(KERN_NOTICE "rock: corrupted directory entry. "
	"extent=%d, offset=%d, size=%d\n",
	rs->cont_extent, rs->cont_offset, rs->cont_size);
	ret = -EIO;
	goto out;
	}

	if (rs->cont_extent) {
	struct buffer_head *bh;

	rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
	if (!rs->buffer) {
	ret = -ENOMEM;
	goto out;
	}
	ret = -EIO;
	if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
	goto out;
	bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
	if (bh) {
	memcpy(rs->buffer, bh->b_data + rs->cont_offset,
	rs->cont_size);
	put_bh(bh);
	rs->chr = rs->buffer;
	rs->len = rs->cont_size;
	rs->cont_extent = 0;
	rs->cont_size = 0;
	rs->cont_offset = 0;
	return 0;
	}
	printk("Unable to read rock-ridge attributes\n");
	}
	out:
	kfree(rs->buffer);
	rs->buffer = NULL;
	return ret;
	}

	/*
	* We think there's a record of type `sig' at rs->chr. Parse the signature
	* and make sure that there's really room for a record of that type.
	*/
	static int rock_check_overflow(struct rock_state *rs, int sig)
	{
	int len;

	switch (sig) {
	case SIG('S', 'P'):
	len = sizeof(struct SU_SP_s);
	break;
	case SIG('C', 'E'):
	len = sizeof(struct SU_CE_s);
	break;
	case SIG('E', 'R'):
	len = sizeof(struct SU_ER_s);
	break;
	case SIG('R', 'R'):
	len = sizeof(struct RR_RR_s);
	break;
	case SIG('P', 'X'):
	len = sizeof(struct RR_PX_s);
	break;
	case SIG('P', 'N'):
	len = sizeof(struct RR_PN_s);
	break;
	case SIG('S', 'L'):
	len = sizeof(struct RR_SL_s);
	break;
	case SIG('N', 'M'):
	len = sizeof(struct RR_NM_s);
	break;
	case SIG('C', 'L'):
	len = sizeof(struct RR_CL_s);
	break;
	case SIG('P', 'L'):
	len = sizeof(struct RR_PL_s);
	break;
	case SIG('T', 'F'):
	len = sizeof(struct RR_TF_s);
	break;
	case SIG('Z', 'F'):
	len = sizeof(struct RR_ZF_s);
	break;
	default:
	len = 0;
	break;
	}
	len += offsetof(struct rock_ridge, u);
	if (len > rs->len) {
	printk(KERN_NOTICE "rock: directory entry would overflow "
	"storage\n");
	printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
	sig, len, rs->len);
	return -EIO;
	}
	return 0;
	}

	/*
	* return length of name field; 0: not found, -1: to be ignored
	*/
	int get_rock_ridge_filename(struct iso_directory_record *de,
	char retname, struct inode inode)
	{
	struct rock_state rs;
	struct rock_ridge *rr;
	int sig;
	int retnamlen = 0;
	int truncate = 0;
	int ret = 0;

	if (!ISOFS_SB(inode->i_sb)->s_rock)
	return 0;
	*retname = 0;

	init_rock_state(&rs, inode);
	setup_rock_ridge(de, inode, &rs);
	repeat:

	while (rs.len > 2) { /* There may be one byte for padding somewhere */
	rr = (struct rock_ridge *)rs.chr;
	/*
	* Ignore rock ridge info if rr->len is out of range, but
	* don't return -EIO because that would make the file
	* invisible.
	*/
	if (rr->len < 3)
	goto out; /* Something got screwed up here */
	sig = isonum_721(rs.chr);
	if (rock_check_overflow(&rs, sig))
	goto eio;
	rs.chr += rr->len;
	rs.len -= rr->len;
	/*
	* As above, just ignore the rock ridge info if rr->len
	* is bogus.
	*/
	if (rs.len < 0)
	goto out; /* Something got screwed up here */

	switch (sig) {
	case SIG('R', 'R'):
	if ((rr->u.RR.flags[0] & RR_NM) == 0)
	goto out;
	break;
	case SIG('S', 'P'):
	if (check_sp(rr, inode))
	goto out;
	break;
	case SIG('C', 'E'):
	rs.cont_extent = isonum_733(rr->u.CE.extent);
	rs.cont_offset = isonum_733(rr->u.CE.offset);
	rs.cont_size = isonum_733(rr->u.CE.size);
	break;
	case SIG('N', 'M'):
	if (truncate)
	break;
	if (rr->len < 5)
	break;
	/*
	* If the flags are 2 or 4, this indicates '.' or '..'.
	* We don't want to do anything with this, because it
	* screws up the code that calls us. We don't really
	* care anyways, since we can just use the non-RR
	* name.
	*/
	if (rr->u.NM.flags & 6)
	break;

	if (rr->u.NM.flags & ~1) {
	printk("Unsupported NM flag settings (%d)\n",
	rr->u.NM.flags);
	break;
	}
	if ((strlen(retname) + rr->len - 5) >= 254) {
	truncate = 1;
	break;
	}
	strncat(retname, rr->u.NM.name, rr->len - 5);
	retnamlen += rr->len - 5;
	break;
	case SIG('R', 'E'):
	kfree(rs.buffer);
	return -1;
	default:
	break;
	}
	}
	ret = rock_continue(&rs);
	if (ret == 0)
	goto repeat;
	if (ret == 1)
	return retnamlen; /* If 0, this file did not have a NM field */
	out:
	kfree(rs.buffer);
	return ret;
	eio:
	ret = -EIO;
	goto out;
	}

	#define RR_REGARD_XA 1
	#define RR_RELOC_DE 2

	static int
	parse_rock_ridge_inode_internal(struct iso_directory_record *de,
	struct inode *inode, int flags)
	{
	int symlink_len = 0;
	int cnt, sig;
	unsigned int reloc_block;
	struct inode *reloc;
	struct rock_ridge *rr;
	int rootflag;
	struct rock_state rs;
	int ret = 0;

	if (!ISOFS_SB(inode->i_sb)->s_rock)
	return 0;

	init_rock_state(&rs, inode);
	setup_rock_ridge(de, inode, &rs);
	if (flags & RR_REGARD_XA) {
	rs.chr += 14;
	rs.len -= 14;
	if (rs.len < 0)
	rs.len = 0;
	}

	repeat:
	while (rs.len > 2) { /* There may be one byte for padding somewhere */
	rr = (struct rock_ridge *)rs.chr;
	/*
	* Ignore rock ridge info if rr->len is out of range, but
	* don't return -EIO because that would make the file
	* invisible.
	*/
	if (rr->len < 3)
	goto out; /* Something got screwed up here */
	sig = isonum_721(rs.chr);
	if (rock_check_overflow(&rs, sig))
	goto eio;
	rs.chr += rr->len;
	rs.len -= rr->len;
	/*
	* As above, just ignore the rock ridge info if rr->len
	* is bogus.
	*/
	if (rs.len < 0)
	goto out; /* Something got screwed up here */

	switch (sig) {
	#ifndef CONFIG_ZISOFS /* No flag for SF or ZF */
	case SIG('R', 'R'):
	if ((rr->u.RR.flags[0] &
	(RR_PX \| RR_TF \| RR_SL \| RR_CL)) == 0)
	goto out;
	break;
	#endif
	case SIG('S', 'P'):
	if (check_sp(rr, inode))
	goto out;
	break;
	case SIG('C', 'E'):
	rs.cont_extent = isonum_733(rr->u.CE.extent);
	rs.cont_offset = isonum_733(rr->u.CE.offset);
	rs.cont_size = isonum_733(rr->u.CE.size);
	break;
	case SIG('E', 'R'):
	ISOFS_SB(inode->i_sb)->s_rock = 1;
	printk(KERN_DEBUG "ISO 9660 Extensions: ");
	{
	int p;
	for (p = 0; p < rr->u.ER.len_id; p++)
	printk("%c", rr->u.ER.data[p]);
	}
	printk("\n");
	break;
	case SIG('P', 'X'):
	inode->i_mode = isonum_733(rr->u.PX.mode);
	set_nlink(inode, isonum_733(rr->u.PX.n_links));
	i_uid_write(inode, isonum_733(rr->u.PX.uid));
	i_gid_write(inode, isonum_733(rr->u.PX.gid));
	break;
	case SIG('P', 'N'):
	{
	int high, low;
	high = isonum_733(rr->u.PN.dev_high);
	low = isonum_733(rr->u.PN.dev_low);
	/*
	* The Rock Ridge standard specifies that if
	* sizeof(dev_t) <= 4, then the high field is
	* unused, and the device number is completely
	* stored in the low field. Some writers may
	* ignore this subtlety,
	* and as a result we test to see if the entire
	* device number is
	* stored in the low field, and use that.
	*/
	if ((low & ~0xff) && high == 0) {
	inode->i_rdev =
	MKDEV(low >> 8, low & 0xff);
	} else {
	inode->i_rdev =
	MKDEV(high, low);
	}
	}
	break;
	case SIG('T', 'F'):
	/*
	* Some RRIP writers incorrectly place ctime in the
	* TF_CREATE field. Try to handle this correctly for
	* either case.
	*/
	/* Rock ridge never appears on a High Sierra disk */
	cnt = 0;
	if (rr->u.TF.flags & TF_CREATE) {
	inode->i_ctime.tv_sec =
	iso_date(rr->u.TF.times[cnt++].time,
	0);
	inode->i_ctime.tv_nsec = 0;
	}
	if (rr->u.TF.flags & TF_MODIFY) {
	inode->i_mtime.tv_sec =
	iso_date(rr->u.TF.times[cnt++].time,
	0);
	inode->i_mtime.tv_nsec = 0;
	}
	if (rr->u.TF.flags & TF_ACCESS) {
	inode->i_atime.tv_sec =
	iso_date(rr->u.TF.times[cnt++].time,
	0);
	inode->i_atime.tv_nsec = 0;
	}
	if (rr->u.TF.flags & TF_ATTRIBUTES) {
	inode->i_ctime.tv_sec =
	iso_date(rr->u.TF.times[cnt++].time,
	0);
	inode->i_ctime.tv_nsec = 0;
	}
	break;
	case SIG('S', 'L'):
	{
	int slen;
	struct SL_component *slp;
	struct SL_component *oldslp;
	slen = rr->len - 5;
	slp = &rr->u.SL.link;
	inode->i_size = symlink_len;
	while (slen > 1) {
	rootflag = 0;
	switch (slp->flags & ~1) {
	case 0:
	inode->i_size +=
	slp->len;
	break;
	case 2:
	inode->i_size += 1;
	break;
	case 4:
	inode->i_size += 2;
	break;
	case 8:
	rootflag = 1;
	inode->i_size += 1;
	break;
	default:
	printk("Symlink component flag "
	"not implemented\n");
	}
	slen -= slp->len + 2;
	oldslp = slp;
	slp = (struct SL_component *)
	(((char *)slp) + slp->len + 2);

	if (slen < 2) {
	if (((rr->u.SL.
	flags & 1) != 0)
	&&
	((oldslp->
	flags & 1) == 0))
	inode->i_size +=
	1;
	break;
	}

	/*
	* If this component record isn't
	* continued, then append a '/'.
	*/
	if (!rootflag
	&& (oldslp->flags & 1) == 0)
	inode->i_size += 1;
	}
	}
	symlink_len = inode->i_size;
	break;
	case SIG('R', 'E'):
	printk(KERN_WARNING "Attempt to read inode for "
	"relocated directory\n");
	goto out;
	case SIG('C', 'L'):
	if (flags & RR_RELOC_DE) {
	printk(KERN_ERR
	"ISOFS: Recursive directory relocation "
	"is not supported\n");
	goto eio;
	}
	reloc_block = isonum_733(rr->u.CL.location);
	if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
	ISOFS_I(inode)->i_iget5_offset == 0) {
	printk(KERN_ERR
	"ISOFS: Directory relocation points to "
	"itself\n");
	goto eio;
	}
	ISOFS_I(inode)->i_first_extent = reloc_block;
	reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
	if (IS_ERR(reloc)) {
	ret = PTR_ERR(reloc);
	goto out;
	}
	inode->i_mode = reloc->i_mode;
	set_nlink(inode, reloc->i_nlink);
	inode->i_uid = reloc->i_uid;
	inode->i_gid = reloc->i_gid;
	inode->i_rdev = reloc->i_rdev;
	inode->i_size = reloc->i_size;
	inode->i_blocks = reloc->i_blocks;
	inode->i_atime = reloc->i_atime;
	inode->i_ctime = reloc->i_ctime;
	inode->i_mtime = reloc->i_mtime;
	iput(reloc);
	break;
	#ifdef CONFIG_ZISOFS
	case SIG('Z', 'F'): {
	int algo;

	if (ISOFS_SB(inode->i_sb)->s_nocompress)
	break;
	algo = isonum_721(rr->u.ZF.algorithm);
	if (algo == SIG('p', 'z')) {
	int block_shift =
	isonum_711(&rr->u.ZF.parms[1]);
	if (block_shift > 17) {
	printk(KERN_WARNING "isofs: "
	"Can't handle ZF block "
	"size of 2^%d\n",
	block_shift);
	} else {
	/*
	* Note: we don't change
	* i_blocks here
	*/
	ISOFS_I(inode)->i_file_format =
	isofs_file_compressed;
	/*
	* Parameters to compression
	* algorithm (header size,
	* block size)
	*/
	ISOFS_I(inode)->i_format_parm[0] =
	isonum_711(&rr->u.ZF.parms[0]);
	ISOFS_I(inode)->i_format_parm[1] =
	isonum_711(&rr->u.ZF.parms[1]);
	inode->i_size =
	isonum_733(rr->u.ZF.
	real_size);
	}
	} else {
	printk(KERN_WARNING
	"isofs: Unknown ZF compression "
	"algorithm: %c%c\n",
	rr->u.ZF.algorithm[0],
	rr->u.ZF.algorithm[1]);
	}
	break;
	}
	#endif
	default:
	break;
	}
	}
	ret = rock_continue(&rs);
	if (ret == 0)
	goto repeat;
	if (ret == 1)
	ret = 0;
	out:
	kfree(rs.buffer);
	return ret;
	eio:
	ret = -EIO;
	goto out;
	}

	static char get_symlink_chunk(char rpnt, struct rock_ridge rr, char plimit)
	{
	int slen;
	int rootflag;
	struct SL_component *oldslp;
	struct SL_component *slp;
	slen = rr->len - 5;
	slp = &rr->u.SL.link;
	while (slen > 1) {
	rootflag = 0;
	switch (slp->flags & ~1) {
	case 0:
	if (slp->len > plimit - rpnt)
	return NULL;
	memcpy(rpnt, slp->text, slp->len);
	rpnt += slp->len;
	break;
	case 2:
	if (rpnt >= plimit)
	return NULL;
	*rpnt++ = '.';
	break;
	case 4:
	if (2 > plimit - rpnt)
	return NULL;
	*rpnt++ = '.';
	*rpnt++ = '.';
	break;
	case 8:
	if (rpnt >= plimit)
	return NULL;
	rootflag = 1;
	*rpnt++ = '/';
	break;
	default:
	printk("Symlink component flag not implemented (%d)\n",
	slp->flags);
	}
	slen -= slp->len + 2;
	oldslp = slp;
	slp = (struct SL_component )((char )slp + slp->len + 2);

	if (slen < 2) {
	/*
	* If there is another SL record, and this component
	* record isn't continued, then add a slash.
	*/
	if ((!rootflag) && (rr->u.SL.flags & 1) &&
	!(oldslp->flags & 1)) {
	if (rpnt >= plimit)
	return NULL;
	*rpnt++ = '/';
	}
	break;
	}

	/*
	* If this component record isn't continued, then append a '/'.
	*/
	if (!rootflag && !(oldslp->flags & 1)) {
	if (rpnt >= plimit)
	return NULL;
	*rpnt++ = '/';
	}
	}
	return rpnt;
	}

	int parse_rock_ridge_inode(struct iso_directory_record de, struct inode inode,
	int relocated)
	{
	int flags = relocated ? RR_RELOC_DE : 0;
	int result = parse_rock_ridge_inode_internal(de, inode, flags);

	/*
	* if rockridge flag was reset and we didn't look for attributes
	* behind eventual XA attributes, have a look there
	*/
	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
	&& (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
	result = parse_rock_ridge_inode_internal(de, inode,
	flags \| RR_REGARD_XA);
	}
	return result;
	}

	/*
	* readpage() for symlinks: reads symlink contents into the page and either
	* makes it uptodate and returns 0 or returns error (-EIO)
	*/
	static int rock_ridge_symlink_readpage(struct file file, struct page page)
	{
	struct inode *inode = page->mapping->host;
	struct iso_inode_info *ei = ISOFS_I(inode);
	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
	char *link = kmap(page);
	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
	struct buffer_head *bh;
	char *rpnt = link;
	unsigned char *pnt;
	struct iso_directory_record *raw_de;
	unsigned long block, offset;
	int sig;
	struct rock_ridge *rr;
	struct rock_state rs;
	int ret;

	if (!sbi->s_rock)
	goto error;

	init_rock_state(&rs, inode);
	block = ei->i_iget5_block;
	bh = sb_bread(inode->i_sb, block);
	if (!bh)
	goto out_noread;

	offset = ei->i_iget5_offset;
	pnt = (unsigned char *)bh->b_data + offset;

	raw_de = (struct iso_directory_record *)pnt;

	/*
	* If we go past the end of the buffer, there is some sort of error.
	*/
	if (offset + *pnt > bufsize)
	goto out_bad_span;

	/*
	* Now test for possible Rock Ridge extensions which will override
	* some of these numbers in the inode structure.
	*/

	setup_rock_ridge(raw_de, inode, &rs);

	repeat:
	while (rs.len > 2) { /* There may be one byte for padding somewhere */
	rr = (struct rock_ridge *)rs.chr;
	if (rr->len < 3)
	goto out; /* Something got screwed up here */
	sig = isonum_721(rs.chr);
	if (rock_check_overflow(&rs, sig))
	goto out;
	rs.chr += rr->len;
	rs.len -= rr->len;
	if (rs.len < 0)
	goto out; /* corrupted isofs */

	switch (sig) {
	case SIG('R', 'R'):
	if ((rr->u.RR.flags[0] & RR_SL) == 0)
	goto out;
	break;
	case SIG('S', 'P'):
	if (check_sp(rr, inode))
	goto out;
	break;
	case SIG('S', 'L'):
	rpnt = get_symlink_chunk(rpnt, rr,
	link + (PAGE_SIZE - 1));
	if (rpnt == NULL)
	goto out;
	break;
	case SIG('C', 'E'):
	/* This tells is if there is a continuation record */
	rs.cont_extent = isonum_733(rr->u.CE.extent);
	rs.cont_offset = isonum_733(rr->u.CE.offset);
	rs.cont_size = isonum_733(rr->u.CE.size);
	default:
	break;
	}
	}
	ret = rock_continue(&rs);
	if (ret == 0)
	goto repeat;
	if (ret < 0)
	goto fail;

	if (rpnt == link)
	goto fail;
	brelse(bh);
	*rpnt = '\0';
	SetPageUptodate(page);
	kunmap(page);
	unlock_page(page);
	return 0;

	/* error exit from macro */
	out:
	kfree(rs.buffer);
	goto fail;
	out_noread:
	printk("unable to read i-node block");
	goto fail;
	out_bad_span:
	printk("symlink spans iso9660 blocks\n");
	fail:
	brelse(bh);
	error:
	SetPageError(page);
	kunmap(page);
	unlock_page(page);
	return -EIO;
	}

	const struct address_space_operations isofs_symlink_aops = {
	.readpage = rock_ridge_symlink_readpage
	};